Data held on a first data storage device may be copied to a second data storage device remote from the first data storage device for data security purposes in a backing-up procedure. Should data on the first data storage device be deleted or damaged, the data can be recovered by accessing the second data storage device over a communication network and, potentially, copying the data back to the first data storage device. The original data on the first data storage device may, itself, be a copy of data held on a primary data storage device.
The communication network has a capacity and much of the capacity of the network may be absorbed in activities other than the copying data between the first and second data storage devices. As such, the capacity of the communication network may be in high demand. Backing-up data is, therefore, usually limited to periods of low network demand. During certain periods backing-up procedures may not be possible due to the level of network usage.